Power Efficient Downlink Beamforming Optimization by Exploiting Interference

We propose a new beamforming scheme for the multi- user multiple-input-single-output (MISO) downlink channel. While conventional beamforming aims at the minimization of the transmit power subject to suppressing interference to guarantee quality of service (QoS) constraints, here we exploit, rather than suppress, the constructive part of interference. By exploiting the power of constructively interfering symbols, the proposed scheme achieves the required QoS at lower transmit power. In addition, we derive an equivalent virtual multicast formulation for the proposed optimization to facilitate the design of a more efficient solver. Our simulation and analysis show significant power savings for small scale MISO downlink channels with the proposed optimization compared to conventional beamforming optimization.